Method of recovery of sulphonic acids from a reaction mixture resulting from sulphuric acid treatment of aromatic oils



which are liquid and which may Patented Apr. 17, 1945 ACIDS FROM ARESULTING TREATMENT assignments, Corpora Massachusetts METHOD OFRECOVERY OF SULPHONI REACTION FROM SULPHURJC ACID F AROMATIC OILS AlfredG. Susie, Melrose, Mass.,

to Fuel Research Development tion, Boston,

MIXT URE assignor, by mesne Mass, a corporation of No Drawing.Application October 8, 1942, Serial No. 461,332

Claims.

This invention relates to the preparation of sulphonic acids and moreparticularly to the separatlon of the sulphonic acids produced by thetreatment of aromatic-rich hydrocarbon oils resultant from anoil-cracking operation and essentially comprising carbon and hydrogenatoms only with sulphonating agents, such as sulphuric acid.

It is the general object of my invention to provide a, simple method forseparating the sulphonic acids producedby the action of a sulphonatingagent on aromatic-rich oils.

This invention is based on the discovery that certain liquid oxygenatedorganic compounds which are only slightly soluble in water, andparticularly those capable of forming oxonium com- Ethers pounds, whenadded in small amounts to the di-.

luted sulphonation-reaction mixture, either before or after the removalof the unsulphonated oils therefrom, will cause a clear separation ofthe sulphonic acids from the aqueous sulphuric acid and from theunsulphonated oil, if present, and will leave an acid solution which maybe fortifled and re-used or from which the acid may be recovered.

More particularly, the oxygenated organic compounds of the naturespecified which are most satisfactory for use in this capacity are thosebe selected from the following classes of organic compounds: namely,alcohols, aldehydes, ketones, esters, ethers, carboxylic acids, phenols,and related compounds. Illustrative examples of compounds falling withinthese classes are:

Alcohols:

Fusel oil Amyl alcohol Butyl alcohol Benzyl alcohol Aldehydes:

Butyraldehyde Salicylaldehyde Heptaldehyde z-ethyl hexanal IBenzaldehyde Ketones:

I Dl-n-propyl ketone Methyl n-propyl ketone Methyl isobutyl ketoneMethyl n-amyl ketone Acetophenone Cyclohezanone Ethyl ether'B,B'-dichloro diethyl ether Benzyl cellosolve Methyl m-tolyl etherVeratrole Phenols:

Phenol Cresol Xylenol Nitrobenzene While capable of general application,this invention has been developed primarily for the treatment of mixedaromatic hydrocarbons, such as may be produced by the cracking of crudepetroleum oils or residues in an upright, externally heated retort, suchfor instance as is shown and described in the prior application ofChatterton and Paffen, Serial No. 332,154, flled' April 29, 1940. I,

The sulphonic acids and their derivatives obtained from thesearomatic-rich oils possess excellent properties, particularly asemulsifying agents and as dispersing agents.

The following example illustrates the separation of the sulphonic acidsfrom a typical sulphonation reaction mixture:'

The aromatic hydrocarbon oil is first. treated with-sulphuric acid,which may be in the proportion of three parts66 Baum sulphuric acid byweight to two parts of aromatic hydrocarbons. The sulphuric acid isadded gradually to the hydrocarbons and the mixture is preferablystirred mechanically and cooled in a water bath during the additionofthe acid. The stirring is then continued at room temperature for aconsiderable period, such as two hours, until the evolution of heatceases, after which the sulphonation mixture is diluted by adding water.The amount of water used at this point in the process may beapproximately equal to the volume of the sulphonation mixture to whichthe water is added.

When this diluted mixture is allowed to 'stand, the unsulphonated oilseparates as a top layer and may be decanted and removed.

After the unsulphonated oil has been removed, I introduce to the dilutedsulphonation mixture approximately 1% by volume of an oxygenated.organic additive which is only slightly soluble in. water and which inthis example is amyl alcohol. This mixture, after vigorous agitation, isthen allowed to stand, and there results a further separation of themixture into an upper brownishblack sulphonic acid layer and a loweraqueous sulphuric acid layer.

The upper layer of aryl sulphonic acids may then be decanted andremoved, leaving the aqueous sulphuric acid for reclamation and furtheruse.

I am aware that separation of sulphonic acids has been suggested by theaddition of watersoluble salts, this being what is sometimes known asthe saltin out process. But this process is not satisfactory for thepurposes contemplated herein, because the salts go into solution in theaqueous acid liquid and contaminate it so that the acid cannot besatisfactorily reclaimed from the solution nor can the acid solution besatisfactorily re-used.

The percentage of the oxygenated organic ad ditive to be used varies indifferent compounds but I have observed that substantial separation ofthe sulphonic acid from the mixture does not begin to take place untilthe concentration of the additive has been increased "sufficiently toprevent foaming. This will be understood by an illustration. Forinstance, if amyl alcohol is to be used and it is found that, when acertain per-- cent of alcohol is added to a specimen of the sulphonicacid mixture, foaming takes place, it will also be found that nosubstantial separation of the sulphonic acid occurs. If the amount ofamyl alcohol is increased until little or no foaming takes place, itwill also be observed that substantial separation of sulphonic acidbegins to occur. This observation forms a convenient guide to determinethe concentration of the particular additive being used.

The aryl sulphonic acids are available for various commercial andindustrial uses, either in acid form or conveniently as aryl sulphonatesby neutralization with any desired base, such as soda ash or lime. Theneutralized product may then be separated from the aqueous liquor byevaporation and the solid residue may be purified, if desired, byextraction with a suitable solvent, such as anhydrous methanol.

By the above-described and relatively simple process, I am able toproduce either aryl sulphonic acids or desired derivatives of such acidsfrom the sulphonation reaction of a complex mixture of hydrocarbons.

The rate of separation of the aryl sulphonic acids from the sulphonationreaction mixture depends to some extent on the amount of oxygenatedorganic additive used, and the rate of separation generally increaseswith an' increase in the amount of additive. The amount of additiverequired also increases somewhat with an increase in the boiling rangeof the aromatic oil.

under treatment. In general, I have found that adding the organicadditive in amounts equal to 1% to 5% of the volume of the reactionmixture produce good results, but under some circumstances amountsoutside of this range may be satisfactorily employed.

The sulphuric acid solution which remains after removal of the arylsulphonic acids may also be utilized in place of water in the dilutionof subsequent sulphonation reaction mixtures. The additive which ispresent in the solution may then immediately cause separation of thesulphonic acids from the sulphonation mixture and the use of additionalseparating agent may not be necessary.

By this procedure, also, the sulphuric acid content of the spent aqueoussulphuric acid may be built up substantially, so that it may beeconomically fortified with sulphur trioxide or oleum and used as asulphonating agent in subsequent sulphonations.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the procedure herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. In the method of recovery of aromatic sulphonic acids from an aqueoussulphonation reaction mixture resulting from sulphuric acid treatment ofaromatic hydrocarbon oils resulted from an oil-cracking operation, thesteps of diluting said reaction mixture with water, and then reducingthe capacity of the aqueous phase for holding the sulphonic acids insolution by adding a liquid oxygenated organic compound which is at mostonly slightly soluble in water and in an amount sufficient only to causthe sulphonic acids to separate from the dilute reaction mixture butsaid additive effecting no substantial solution of the sulphonic acidsin the additive.

2. The method as set forth in claim 1, in which the volume of theadditive is in the amount of 1% to 5% of the volume of the dilutedreaction mixture.

3. The method as set forth in claim 1, in which the sulphonationreaction mixture is diluted by adding water containing some part of thedilute sulphuric acid recovered from a previous separating operation andhaving some proportion of oxygenated additive therein.

4. The method of recovery of sulphonic acids as set forth in claim 1, inwhich the additive,

is selected from the following classes of oxygenated organic compounds:namely, alcohols, ketones, esters, aldehydes, ethers, carboxylic acidsand phenols which are at most only slightly soluble in water.

5. In the method of recovery of aromatic sulphonic acids from an aqueoussulphonation reaction mixture resulting from sulphuric acid treatment ofaromatic hydrocarbon oils resultant from an oil-cracking operation, thestep of diluting said reaction mixture with water, then reducing thecapacity of the aqueous phase for holding the sulphonic acids insolution by adding a liquid oxygenated organic compound which is at mostonly slightly soluble in water and in an amount sufficient only to causethe sulphonic acids to separate from the dilute reaction mixture butsaid additive effecting no substantial solution of the sulphonic acidsin the additive, and then removing the separated sulphonic acids bydecantation.

ALFRED G. SUSIE.

